This research project has been planed to develop a spatial power-combining oscillator using integrated solid-state devices as a practical millimeter-wave radiation source. The oscillator combines coherent radiation powers from a large number of solid-state source devices such as Gunn diodes, resonant tunneling diodes (RTD's), and HEMT's in a quasi-optical resonator, and consequently produces an intense radiation power. In this project, two types of quasi-optical resonators have been developed. One of them is a metal grooved mirror type Fabry-Perot (GFP) resonator for the used of a large number of HEMT's and the other is an overmoded-waveguide resonator with an array of TE10 mode waveguides containing Gunn diodes. The theoretical and experimental results are as follows,1. An efficiency of about 83 % and an output power of 1.5 W (continuous wave) at 60 GHz band has been achieved with a 3x3 waveguide Gunn diode array.2. The overmoded waveguide oscillator at 100GHz band has been successful
… Morely developed. The oscillator with a 3x3 waveguide Gunn diode array has produced 0.45 W with an efficiency of more than 50% at 98 GHz. These results indicate that the overmoded waveguide resonator for spatial power combining of solid state devices is very useful for producing intense millimeter waves.3. The equivalent circuit for the overmoded waveguide oscillator has been developed to design the resonator.4. The equivalent circuit for the GFP-oscillator with a HEMT array has been theoretically developed and experimentally verified at frequencies between 10 and 30 GHz. In addition, a new resonator configuration for the oscillator is developed to incorporate a large HEMT array into the resonator easily.5. In order to use resonant tunneling diodes (RTD) in the GFP-resonator in a submillimeter wave region, removal of spurious oscillations usually produced by conventional RTD oscillators, using series connection has been investigated. The theoretical and experimental results have shown that the series connected RTD's do not produce the unwanted low frequency oscillations. Less